accept VirtualizationType with register
rename virtuliazation type column
add virtualiza-type in describe-image response
fix for null virtualization type images
set root-vbr type to disk for hvm emis
set eki,eri null for hvm emi
VirtuationType should be in MachineImageInfo and BlockStorageImageInfo; Kernel/ramdisk resolution passthrough
fix build failure
use vbr type = boot
vbr type=machine
rootDevice=sda for linux hvm
libvirt.xsl change to accept linux hvm
EUCA-6887: accept linux HVM disk at registration time

The following changes were made to enable Linux HVM disk. Manually tested and confirmed working.
– register operation accepts --virtualization-type=hvm from the latest euca2ools
– ImageInfo has virtualization-type field (should implement upgrade)
– when the EMI's virtualiation-type==hvm, the VBR sent to NC has basically the same format as Windows EMI.
– libvirt.xsl has been slightly changed to account for hvm.